Means for controlling the charging of storage batteries.



110. 787,024. PATENTED' APR. 11, 1905. R. N. CHAMBERLAIN. MEANS FORCONTROLLING THE CHARGING OP STORAGE BATTERIES.

APPLICATION I ILBD FEB. 8, 190 4.

Z. fiwi Midefies/ Patented April 11, 1905.

UNITED STATES PATENT OEEIcE.

RUFUS N. CHAMBERLAIN, OF DEPEW, NEW YORK, ASSIGNOR TO GOULD STORAGEBATTERY COMPANY, OF NEW YORK, N. Y.

MEANS FOR CONTROLLING THE OHARGlNG OF STORAGE BATTERIES.

SPECIFICATION forming part of Letters Patent NO. 787,024, dated April11, 1905.

Application filed February 8, 1904. Serial No. 192,514.

To all whom it rim/y concern:

Be it known that 1, Burns N. CHAMBERLAIN,

a citizen of the United States, and a resident of Depew, in the countyof Eric and State of New York, have invented a new and usefulImprovement in Means for Controlling the Charging of Storage Batteries,of which the following is a specification.

This invention relates to means for charging storage batteries, and moreparticularly to a device for automatically opening the charging-circuitwhen the battery is sutlicientl y charged or brought to a predetermineddesired condition of charge.

It is not always practical to charge a battery at a definite rate,because sometimes the time allowed for charging is short, requiring thecharging rate to be abnormally high, while at other times the periodduring which the battery might be charged is long, when a low chargingrate can be used. It is a matter of common knowledge in storage-batteryengineering that the back pressure from the battery in charging is moreor less in proportion to the charging rate, increasing as the chargingrate rises and decreasing as it lowers. Attempts have been heretoforemade to antomatically open the charging-circuit when the battery wasproperly charged by a switch operated by an electromagnet having asingle coil connected across the battery; but these devices have beenunreliable or useless in practice, for the reason that they would openthe charging-circuit at varying stages of the charging operationaccording to the variations in the charging rate, thus at times openingthe circuit before the battery was fully charged and at other timespermitting an overcharge.

The object of this invention is to remedy these defects and provide anefiicient and practical means which will enable an operator to put anordinary storage battery on charge at whatever rate is convenient ornecessary at the time and which will automatically open thecharging-circuit only when the battery is charged to the predetermineddesired extent regardless of the rate of charge and the changes in thevoltage of the charging-circuit during the charging process, whereby thebat tery only consumes the amount of power that it properly requires andprevents the waste due to overcharging. This result is accomplished inthe device hereinafter described by providing the switch-controllingmagnet with a coil connected across a shunt of the charging-circuit andacting di'lferentially relative to the other coil which is connectedacross the battery.

The accompanying drawing illustrates diagrammatically means cn'ibodyingthe invention for automatically opening the chargingcircuit when thebattery is charged to the predetermined desired extent.

Referring to the drawing, B represents the storage battery or batteries,and l) the dy namo or generator for charging the battery and which isconnected to one terminal of the battery by a conductor (1 and to theother terminal of the battery by conductors (Z and (Z which areconnected by a switch E. The movable blade or lever E of this switch ismoved by hand into contact with the stationary blade to close thechargii'i-g-circuit and place the battery on charge and is held inclosed position by a suitable latch F, which is automatically operatedwhen the battery is charged to the predetermined amount to release theswitch-blade, which is moved by a spring (3 or other device to open thecharging circuit.

The latch F for releasing the switch lever or blade in the constructionillustrated constitutes the armature of an electromagnet G, which isprovided with an energizing-coil in a normally open circuit 0 connectedacross the battery or to any other source of electric energy. Thiscircuit is closed when the battery is charged by an automatic or pilotmagnet H, which is provided with an energizing or magnetizing coil H,connected across the battery by conductors it h, and a secondditferentially-wound or opposing coil H which is connected across ashunt if it" of the charging-circuit. hen the battery is charged to thedesired extent, the pilot-magnet attracts its armature H, therebyplacing the normally separated contacts I and I, which are connectcd tothe conductors of the coil for the latch-operating magnet, in contactand closing the circuit to energize the magnet, which attracts the latchF and releases the switchlolade, so that the latter is moved by itsspring to open the charging-circuit.

The operation of the device is as follows: The operator closes theswitch E to place the battery on charge and adjusts the charging rateaccording to the time allowed for the battery to receive a full charge.The entire amount of currrent passing through the battery or batterieswill pass through the conductor (Z of the charging-circuit, the shunt71, ]L3, and the coil H. of the pilot-magnet connected thereto, and theother coil, H, of the pilot-magnet will also be energized. If thecharging rate of the battery increases, the amount of current passingthrough the shunt also increases, thus increasing the energization ofthe shunt-coil H of the pilot-magnet and compensating for theundesirable augmentation of the energization of the other coil, H, ofthe pilot-magnet, due to the increased back pressure from the battery.Supposing, for example, that the average charging rate ofthe battery issixty amperes, then when the battery is being charged at this rate itwould near the end of its full charge have its back pressure raised to apoint which would indicate a full charge. This pressure exerted on themagnetizing-coil H of the pilot-magnet predominates over theenergization of the opposing coil H thereof sufficiently to attract itsarmature and close the energizing-circuit r/ r of the latch-operatingmagnet, which attracts the latch and releases the switch-blade. If,however, on account of limited time it is necessary to raise thecharging rate of the battery to ninety arnperes, for instance, the backpressure from the battery when fully charged would be decidedly higherthan the back pressure given when being charged by sixty amperes. Theincreasing charging rate also produces an increased energization in theshunt /L2 A." and opposing coil H of the pilotmagnet, the effect ofwhich is to modify to a greater degree the action of the magnetizingcoilH than when the battery was being charged at the sixty-ampere rate, andthe net magnetic e'llect on.the pilot-magnet would be practically thesame as when the battery was being charged at the sixty-ampere rate. Onthe other hand, suppose that the period allowed for charging the batteryis longer than usual and instead of charging at the normal charging ratea thirty-ampere rate was used. In this case the battery back pressurewould not rise to as high apoint as it did at the sixty-ampere rate; butthe opposing coil H would have less magnetic effect on the pilot-magnet,leaving the net magnet effect on the pilot-magnet the same as when thebattery was being charged at a sixty-ampere rate.

From the above it will be apparent that the attendant can simply closethe switch E and adjust the charging rate according to the time allowedfor fully charging the battery and without further attention the batterywill receive a substantial charge, when the pilotmagnet A will cause theswitch to open. Another advantage of the means described is that itspractical operation is not affected by variations of the voltage in thecharging-circuit during the charging operation. If the voltage of thegenerator or charging circuit should rise during the charging operation,the charging rate would change from the normal to an excessively highrate, or if the voltage was reduced the charging rate would lower. Ineither case the shunt-coil H" of the pilotmagnet would balance theeffect produced by either an increase or decrease in the charging ratefrom that at which it had been started.

I claim as my invention 1. The combination of a storage battery, acharging-circuit for the same, a hand-closed switch in said circuit forclosing the same, a device which opens the switch automatically when theswitch is released, means for holding the switch closed, and anelectromagnetic releasing device for said holding means containingdifferential windings which cause the magnetic effect to vary inverselyin accordance with variations in the charging rate of thecharging-circuit, substantially as set forth.

2. The combination of a storage battery, a charging-circuit for thesame, a hand-closed switch in said circuit for closing the same, adevice which opens the switch automatically when the switch is released,means for holding the switch closed, and an electromagnetic releasingdevice for said holding means, which releasing device contains amagnetizing-coil connected across the battery and an opposing coilconnected across a shunt of the chargingcircuit, substantially as setforth.

3. The combination with a storage battery, and a charging-circuit, of aswitch in said charging-circuit, an electromagnet for opening saidswitch, a normally open energizingcircuit for said magnet, apilot-magnet for closing said normally open circuit, and means forvarying the magnetic effect of said magnet in inverse correspondencewith the variations in the charging rate of the charging-oircuit,substantially as set forth.

4E. The combination with a storage battery and acharging-circuit for thesa1ne,of a switch 1 energizing-circuit for said switclvoperating l insaid charging-circuit, an electromagnet for magnet, substantially as setforth. IO opening said switch, a normally open ener- Witness my handthis 30th day of January, gizing-circuit for said magnet, a pilot-magnet1904.

having difl'erential windings connected respec- RUFUS N. CHAMBERLAIN.tively across the battery and across a shunt of Witnesses:

the energizing-aimuit, and an armature which CHAS. XV. PARKER,

is operated by said pilot-magnet to close the C. B. HORNBECK.

